Light-sensitive image sensors such as focal plane array (FPA) devices include a photodiode array (PDA) packaged with a read out integrated circuit (ROIC). Many different FPA package configurations are available including, for example, leaded and leadless packages. Each conventional package type for FPA can include various shared characteristics.
FIG. 3 depicts a schematic cross-section of an FPA device 200 packaged as a leadless chip carrier (LCC). FIG. 3 includes a ceramic, plastic, or resin carrier body 202 including internal traces 204 electrically coupled to external pads or castellations 206. The external pads 206 can be surface mounted to a circuit board using a conductor, or the device 200 can be placed into an LCC socket. FIG. 3 further depicts a ROIC 208 physically attached to the carrier 202 using an adhesive 210. Bond wires 212 electrically couple bond pads (not individually depicted for simplicity) on the ROIC 208 to the traces 204 within the carrier body 202 such that circuitry on the ROIC 208 can be electrically accessed through the external pads 206. A PDA 214 is mounted to the upper surface of the ROIC 208 using a nonconductive adhesive (not individually depicted for simplicity). Other bond wires 218 electrically couple circuitry on the PDA 214 to circuitry on the ROIC 208. A package lid 216 hermetically sealed to the carrier 202 includes a clear window 216A that exposes the PDA 214 to external light. In the device 200 of FIG. 3, the carrier 202 is configured such that the lower surface of the lid 216 does not contact the loop in the bond wires 212, 218. FPAs including ROICs and PDAs provided in different package styles are well known.
Design goals for semiconductor device engineers include providing devices having smaller dimensions, a reduced cost, and improved reliability. A device design that helped to accomplished one or more these goals would be desirable.